| Description |
A quarter of the 50,000 amputations per year are upper-limb. The current upper-limb prostheses are either invasive and/or provide ineffective intuitive control. This leads to their low acceptance rates. A potential solution that has been explored by the researchers is surface electromyography (sEMG) that uses electrodes placed on the surface of the arm to control the prosthesis. The number and placement of these electrodes are often chosen semi-arbitrarily and do not allow the user to control motions with multiple degrees of freedom (DOFs). The aim of this research is to better determine the optimal realistic number and placement of the electrodes to provide more accurate and intuitive control of upper-limb prostheses. The sEMG data of 5 intact subjects controlling 8 degrees of freedom were gathered using 96 electrodes distributed evenly across the forearm. The Root Mean Square Error (RMSE) between the computer's prediction of the subject's movement and the computer's pre-programmed movement was computed and compared with an increasing number of electrodes. Firstly, the data analysis showed that some electrodes out of the total 96 were chosen more frequently than others as they had the most unique signals. Secondly, when the electrodes were utilized in order from the one having the most unique signal to the least, approximately 50 electrodes were required for accurate control of the prosthesis, compared to the 90 electrodes needed when selected in the opposite order. Based on current results, approximately 50 ideally chosen electrodes placed in the respective areas on the arm are required to control 8 DOFs. This research will help the researchers to optimize sEMG control more effectively and thus provide more accurate control of myoelectric upper-limb prostheses. |
